methodology, why not contributed

Author: homm

README.md

@@ -52,32 +52,32 @@ the result will be 61.7 Mpx/s.
 - Pillow 3.2.0
 - Pillow-SIMD 3.2.0.post1
 
-Source    | Operation           | Filter  | IM   | Pillow | SIMD SSE4 | SIMD AVX2 
-----------|---------------------|---------|------|--------|-----------|-----------
-7712x4352 | Resize to 16x16     | Bilinear| 27.0 | 217    | 456       | 545
-          |                     | Bicubic | 10.9 | 115    | 240       | 278
-          |                     | Lanczos | 6.6  | 76.1   | 162       | 194
-          | Resize to 320x180   | Bilinear| 32.0 | 166    | 354       | 410
-          |                     | Bicubic | 16.5 | 92.3   | 198       | 204
-          |                     | Lanczos | 11.0 | 63.2   | 133       | 147
-          | Resize to 2048x1155 | Bilinear| 20.7 | 87.6   | 202       | 217
-          |                     | Bicubic | 12.2 | 65.7   | 126       | 130
-          |                     | Lanczos | 8.7  | 41.3   | 88.2      | 95.6
-          | Blur                | 1px     | 8.1  | 17.1   | 37.8
-          |                     | 10px    | 2.6  | 17.4   | 39.0
-          |                     | 100px   | 0.3  | 17.2   | 39.0
-1920x1280 | Resize to 16x16     | Bilinear| 41.6 | 196    | 422       | 489
-          |                     | Bicubic | 18.9 | 102    | 225       | 263
-          |                     | Lanczos | 13.7 | 68.6   | 118       | 167
-          | Resize to 320x180   | Bilinear| 27.6 | 111    | 196       | 197
-          |                     | Bicubic | 14.5 | 66.3   | 154       | 162
-          |                     | Lanczos | 9.8  | 44.3   | 102       | 107
-          | Resize to 2048x1155 | Bilinear| 9.1  | 20.7   | 71.3      | 72.6
-          |                     | Bicubic | 6.3  | 16.9   | 49.3      | 54.3
-          |                     | Lanczos | 4.7  | 14.6   | 36.8      | 40.6
-          | Blur                | 1px     | 8.7  | 16.2   | 35.7
-          |                     | 10px    | 2.8  | 16.7   | 35.4
-          |                     | 100px   | 0.4  | 16.4   | 36.2
+Source    | Operation               | Filter  | IM   | Pillow | SIMD SSE4 | SIMD AVX2 
+----------|-------------------------|---------|------|--------|-----------|-----------
+7712x4352 | **Resize to 16x16**     | Bilinear| 27.0 | 217    | 456       | 545
+          |                         | Bicubic | 10.9 | 115    | 240       | 278
+          |                         | Lanczos | 6.6  | 76.1   | 162       | 194
+          | **Resize to 320x180**   | Bilinear| 32.0 | 166    | 354       | 410
+          |                         | Bicubic | 16.5 | 92.3   | 198       | 204
+          |                         | Lanczos | 11.0 | 63.2   | 133       | 147
+          | **Resize to 2048x1155** | Bilinear| 20.7 | 87.6   | 202       | 217
+          |                         | Bicubic | 12.2 | 65.7   | 126       | 130
+          |                         | Lanczos | 8.7  | 41.3   | 88.2      | 95.6
+          | **Blur**                | 1px     | 8.1  | 17.1   | 37.8
+          |                         | 10px    | 2.6  | 17.4   | 39.0
+          |                         | 100px   | 0.3  | 17.2   | 39.0
+1920x1280 | **Resize to 16x16**     | Bilinear| 41.6 | 196    | 422       | 489
+          |                         | Bicubic | 18.9 | 102    | 225       | 263
+          |                         | Lanczos | 13.7 | 68.6   | 118       | 167
+          | **Resize to 320x180**   | Bilinear| 27.6 | 111    | 196       | 197
+          |                         | Bicubic | 14.5 | 66.3   | 154       | 162
+          |                         | Lanczos | 9.8  | 44.3   | 102       | 107
+          | **Resize to 2048x1155** | Bilinear| 9.1  | 20.7   | 71.3      | 72.6
+          |                         | Bicubic | 6.3  | 16.9   | 49.3      | 54.3
+          |                         | Lanczos | 4.7  | 14.6   | 36.8      | 40.6
+          | **Blur**                | 1px     | 8.7  | 16.2   | 35.7
+          |                         | 10px    | 2.8  | 16.7   | 35.4
+          |                         | 100px   | 0.4  | 16.4   | 36.2
 
 
 ### Some conclusion
@@ -92,7 +92,20 @@ All tests done on Ubuntu 14.04 64-bit runing on
 Intel Core i5 4258U with AVX2 CPU on single thread.
 
 ImageMagick performance measured with command-line tool `convert` with
-`-verbose` and `-bench` arguments
+`-verbose` and `-bench` arguments. I'm using command line because
+I needed to test latest version and this is to easist way to do that.
+All operations are producing exactly the same result.
+Resizing filters compliance:
+
+- PIL.Image.BILINEAR == Triangle
+- PIL.Image.BICUBIC == Catrom
+- PIL.Image.LANCZOS == Lanczos
+
+In ImageMagick the radius of gaussian blur called sigma and second parameter
+is called radius. In fact there should not be additional parameters for
+*gaussian blur*, because if the radius is too small, this is *not*
+gaussian blur anymore. And if the radius is big, this does not give any
+advantages, but makes operation slower. For test I set radius to sigma × 2.5.
 
 Following script were used for testing:
 https://gist.github.com/homm/f9b8d8a84a57a7e51f9c2a5828e40e63
@@ -109,6 +122,18 @@ benchmakrs. And result is
 
 ## Why not to contribute SIMD to the original Pillow
 
+Well, this is not so simple. First of all, Pillow support large number
+of architectures, not only x86. But even for x86 platforms Pillow orfen
+distributed via precompiled binaries. To integrate SIMD in precompiled binaries
+we need to do runtime checks of CPU capabilites.
+To compile code with runtime checks we need to pass `-mavx2` option
+to compiller. But this automaticaly activates all `if (__AVX2__)` and below
+conditions. And SIMD instructions under such conditions are exist
+even in standard C library and they do not have any runtime checks.
+Currently I don't know a way how to tell to compiller to allow SIMD
+instrustions in the code but *do not allow* using such instructions without
+runtime checks.
+
 
 ## Installation